Crimping method and apparatus



Oct. 15, 1957 w. F. BROSKE CRIMPING METHOD AND APPARATUS Filed March 14, 1956 2 Sheets-Sheet l INVENTOR,

WiHium F BYoske United States Patent 6 2,809,546 CRIMPING METHOD AND APPARATUS William F. Broske, Camp Hill, Pa., assignor to AMP Incorporated, a corporation of New Jersey Application March 14, 1956, Serial No. 571,443 9 Claims. (Cl. 81-15) This invention relates to a method of forming crimped connections and to an apparatus particularly, but not necessarily exclusively, intended for practicing the method.

An object of the invention is to provide a simplified and compact apparatus for forming a crimped connection between a tubular ferrule and a wire or the like.

It is a further object of the invention to provide a crimping apparatus providing a plurality of independently movable crimping dies in which a major portion of the available crimping force is subsequentially applied to each of the dies in such manner as to partially crimp the ferrule while a minor portion of the available force is applied to the remaining die or dies.

It is a further object of the invention to provide a crimping apparatus capable of applying a crimping force sequentially and repeatedly to the external surface of a ferrule at two or more areas thereby to crimp the ferrule onto a wire or the like by stepwise deformation of the ferrule.

It is a further object of the invention to provide a crimping device operable for crimping relatively large ferrules by the use of a relatively small crimping force such as can be developed manually or with a simple pneumatic or electrical power source.

It is a further object of the invention to provide a crimping method for a ferrule in which the crimp is formed by stepwise deformation of the ferrule at two or more areas.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms each as may be best suited to the conditions of a particular use.

In the drawings:

Figure 1 is a perspective view of a preferred embodiment of an apparatus constructed in accordance with the principles of the invention;

Figure 2 is a view taken along the lines 2-2 of Figure 1;

Figure 3 is a fragmentary view of a crimping die which forms part of the invention;

Figure 4 is an enlarged view of the end of a power screw which forms part of .the invention;

Figure 5 is a perspective view of a terminal of a type crirnpable by the practice of the invention;

Figure 6 shows the terminal of Figure 5 as crimped onto the end of a wire;

Figures 7A, 7B, 7C, 7D and 7E are fragmentary views illustrating the operation of the embodiment of Figure l;

2,809,546 Patented Oct. 15, 1957 ice Figure 8 is a graphical representation of movement of the indentors in the operation of the embodiment of Figure l; and

Figure9 is a perspective view of a bearing block which forms part of the invention.

In the apparatus embodiment shown in Figures 1 and 2 the reference numeral 2 indicates a base from which extend a pair of spaced parallel sidewalls 4 which are preferably either integral with the base or secured thereto as by welding. A nest 6 providing a ferrule receiving cavity 8 is removably positioned between the sidewalls by means of a dowel 10 which extends through aligned apertures in the nest and sidewalls,

A cap piece 12 is secured at each end to the top of one of the sidewalls 4 by means of machine screws 14 and provides a threaded aperture intermediate its ends for the reception of an actuator screw or power screw 16. A pair of identical actuated members comprising bearing blocks 18, one of which is shown in perspective in Figure 9, are secured to the cap piece by suitable means such as the disclosed screws 20 and depend down wardly between sidewalls 4. Each of these bearing blocks provides a groove 22 on one face thereof and the total thickness of the two blocks is preferably such that they fit relatively snugly between upstanding sidewalls 4 when the cap is in the assembled position of Figure 1. The lower portion of each block is cut away as indicated at 26 to permit positioning of a terminal on the anvil as shown in Figure 2.-

The two grooves 22 when disposed face to face define a through aperture 24 which slidably accommodates a pair of identical crimping dies 28a, 2812. As shown by the View of indcntor 28a in Figure 3, each of these dies provides an indenting portion 301 on one edge thereof which tapers towards a rounded indenting edge, and a bearing nub 32a. This bearing nub is not a symmetrical protuberance but provides a high point 34a which is located adjacent one of the faces 36a of the indentor. The indentors are so dimensioned as to provide a sliding fit within aperture 24 and it is therefore necessary to provide a means for retaining them within the aperture when the apparatus is not in use and a terminal is not positioned on nest 8. To this end each of the indentors is recessed as indicated at 38a, 33b for the accommodation of the end of a set screw 40 which extends threadedly through aligned apertures in sidewalls 4 and bearing members 18. By this means the indentors are prevented from falling out of aperture 24 although they are permitted the limited movement required for the indenting operation.

The high points 34a, 34b of the bearing nubs of the indentors are contacted by the lower end of power screw 16 which lower end constitutes a bearing face indicated by reference numeral 17. In the disclosed embodiment the line of contact between this bearing face and the bearing nubs extends around the end of the screw near the periphery thereof although in alternative embodiments the line of contact might be either closer to .or further removed from the axis of the power screw.

Bearing face 17 of the power screw is beveled as shown in Figure 4. The proper angle X for this bevel is defined by the formula Where p is the pitch of the threads of the power screw and d is the component which extends normally to the axis of the power screw between the contact points 34a, 34b. The points of contact 34a, 3412 are on diametrically opposite sides of the axis of the power screw and are equidistant from the axis. In the particular apparatus disclosed, the beveled face 17 of the power screw is com tacted along its periphery, however, alternative embodi- V as the terminal shown in relatively freely slidable in aperture ments in which the bearing nubs 32a, 32b contact the power screw on a shorter radius are feasible. Referring to Figure 4 (which shows the pitch of the threads in exaggerated size in the interest of clarity of illustration) it can be seen. that where the angle ofthe bevelis as given above, the point 27 will be displaced from the point a distance p/2 along the axis of the power screw which is equal to one-half of the pitch of the threadsso that if the power screw is turned one half of a revolution, the point 27 will occupy the same position as the point 25 previously occupied. a

V The upper end of the power screw provides a noncircular portion which is adapted to receive a suitable wrench su'ch as a tap wrench as shown. If desired, electric or pneumatic drive'means may be provided for developing the necessary torque. An adjustablestop 44 incorporating a set screw is threaded onto the upper end of the power screw for the purpose of limiting its movement to thereby limit the displacement of the indentors 28a, 28b. In operation, the ferrule portion 46 of a terminal such Figure 5, is positioned on nest 6beneath dies 23a, 23b and thebared end 48 of a conductor C is inserted into the ferrule. Since the dies are 24, it will usually be found thatit is necessary to lift digitally the dies in order :to permit positioning of the ferrule in cavity 8. Thereafter the necessary force is applied to turn power screw 16 through the number of revolutions required to indent ferrule 46 upon itself to form a crimped connection of thetype shown at 46' of Figure 6.

During rotation of'the power screw, the dies are alternately urged downwardly through a relatively small increment of their total travel. As shown by Figures 7A 7E,[as power screw 16 is turned one-half of a revolution in the direction of the arrow from Figure 7A, the point 25 on the face of the power screw is brought into contact with bearing nub 32b at 34b. Since the power screw itself is lowered by a distance p/2 and since point 25 is removed from the point 27 by a distance of p/2 (as measured along the power screw axis), indebtor 28b is urged downwardly a distance p during this half revolution of the power screw. During this same interval, indentor 23a remains substantially stationary for the reason that as the power screw moves downwardly, this downward motion is offset by the fact that the point 27 on thebearing surface of the power screw is brought into contact with hearing nub'34t z. However, while indentor 28a is not displaced downwardly during this interval, this indentor is retained against the surface of the ferrule 45 without being allowed to relax to any substantial extent. The movement of the indentors is clearly depicted in Figure 8 which shows the alternating dwells and displacements of the indentors.

According to the method aspect of the instant invention, the ferrule46 is indented by alternate application of an indenting force at two locations on its surface. A notable advantage of this method is that the crimped connection will be found to have a higher central ridge between indentations than in the case where the two indentors are driven into the ferrule simultaneously. As shown in Figure 6 at 50, the top of the ridge separating the indentations 52 is of substantially the same height as the sides of the crimped ferrule and this feature of'the crimp cointributes to its overall strength. Also, I'have found upon visual examination of sectioned crimped connections that the ferrule wall thickness at the bottom of the indentations is greater where the crimp 'is made in accordance with the instant method than is the case where the two indentors are simultaneously driven iuto'theferrule46. 7 7

'It is'm'y belief that the advantages of a higher central ridge 50;and a thicker metal thickness at the bottoms of the indentations 52 can be explained as follows. Since the ferrule 46 is slowly and incrementally indented during the descent of the power screw and since the indenting force is applied to only one of the indentations 52 at a time, the flow pattern of the metal of the ferrule is somewhat different than is the case where both indentors are driven into the ferrule simultaneously. In the practice of the instant invention, the metal of the ferrule is permitted to flow into the space separating the indentor portions 30a, 30b to a greater extent since metal flows into this space first from one side and thenfrom the other side as the indentors 28a, 28b are alternately actu ated. Referring again to Figures 7A7E, it can be seen thatduring the first of rotation of the power screw, metal flows from the right into the space separating the indentor portionsfitia, 30b as indentor 28b descends. During the next 180 of rotation of the screw (Figures and 7E) metal flows into this same space on y from the left as indentor 28a descends. By contrast, if thetwo-indentors were actuated simultaneously, metal would tend to flow into the space separating indentor portions 30a, 3912 from both sides simultaneously but since the directions of flow would be opposed to each other, less metal wouldactually enter this space and longitudinal extrusion would take place instead.

An additional advantage of the invention stems from the fact where the conductor is multi-stranded, as shown in Figure 5, the strands are kneaded and shifted during initial portions of the indenting process and as a result are closely packed before being clinched by the ferrule. This results in a more uniform crimp with less void space and improved conductivity.

I prefer to provide the critical angle discussed above in the face of the power screw since where the screw is beveled in this manner, the inactive one of the indentors will not relax as the other indentor is driven into the ferrule. This prevents any rolling of the ferrule on its anvil and additionally prevents any change in shape of the partially formed indentation as a result of the action of the other indentor. However, under some circumstances, particularly where the ferrule is comparatively large and the indentors comparatively'small, it might be found practical to provide a steeper angle of bevel in the face of the power screw than the critical angle so that the inactive indentor is not maintained against the ferrule without relaxation.

The instant method of forming a crimp by alternate actuation of two or more indentors can be practiced with devices quite dissimilar from the apparatus of Figure 1. For example, in Figure 11 of my copending application, Serial No. 553,944, filed December 19, 1955 for Electrical Connections, I disclose a crimper providing a pair of independently actuatable indenting cams which are alternately rotated through a minor arc progressively to indent a ferrule upon itself. It will be apparent to those skilled in the art that the inventive concept of the instant method is practiced in the operation of the device shown in Figure 11 of this copending application. The inventive concept of the present method requires two or more crimping dies or indentors which are'urged, one at a time, through a portion of their total displacement until. the crimp is completed.

Changes in construction will occur to those skilled in the art and various apparently diflerent modifications and embodiments may be made without departing from the scope of the invention. .The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

I claim:

1. A device for crimping a ferrule comprising a ferrulereceiving nest and a plurality of crimping dies, each of, said dies being independently movable towards said nest and into crimping relationship with a ferrule positioned.

thereon, and means for incrementally moving said dies in sequential order into indenting relationship.

2. A device for crimping a ferrule comprising a ferrulereceiving nest, at least two crimping dies, each of said dies being independently movable towards said nest and into crimping relationship with a ferrule positioned thereon, and die actuating means for moving each of said dies in sequence independently of the others through an increment of its total crimping travel whereby said ferrule is progressively crimped by each of said dies, said die actuating means being operative to prevent substantial movement of any of said dies away from said ferrule during the crimping process and while another of said dies is being moved toward said ferrule.

3. A device for crimping a ferrule comprising a ferrulereceiving nest, a pair of crimping dies movable along a confined path toward said nest and into crimping relationship with a ferrule positioned thereon and a threaded power screw having a bearing face engageable with said dies whereby upon rotation of said power screw said dies are moved along said confined path.

4. A device as set forth in claim 3 wherein said bearing face of said power screw is beveled on an angle whose tangent is equal to one half of the pitch of the threads of said power screw divided by the distance separating the bearing portions of said dies whereby said indentors are urged in alternating order along said path a distance substantially equal to the pitch of said threads.

5. A device for crimping a ferrule comprising a ferrulereceiving nest and a power screw mounted for movement upon rotation thereof towards and away from said nest, at least two indentors interposed between said power screw and said nest, said indentors being independently movable along confined paths extending parallel to the axis of said power screw into indenting relationship with a ferrule positioned on said nest, said power screw providing a beveled bearing surface on the end thereof adjacent said indentors whereby upon rotation of said power screw with concomitant movement thereof toward said nest, said indentors are independently and alternately urged into indenting relationship with said ferrule.

6. A mechanical motion device comprising an actuator screw having a beveled bearing face on one end thereof and a pair of actuated members, each of said members having a bearing surface engageable with said beveled bearing face whereby upon rotation of said actuator screw with concomitant axial movement thereof, said actuator members are displaced one at a time along the direction of movement of said actuator screw.

7. A mechanical motion device comprising an actuator screw having threads of pitch p on the surface thereof and having a beveled bearing face on one end thereof,

and a pair of actuated members having bearing surfaces engageable with said bearing face at diametrically opposite locations equidistant from the axis of said screw, the bevel on said face being at an angle X defined by the formula where d is equal to a component of the distance separating said diametrically opposite locations which component extends normally of the axis of said power screw whereby upon rotation of said actuator screw with concomitant movement thereof in an axial direction said actuated members are displaced one at a time a distance p in the direction of axial movement of said actuator screw and at any given time the actuated member which is not being so displaced is retained against movement in the direction opposite from the direction of movement of said actuator screw.

8. A method of crimping a ferrule onto a wire received therein comprising the steps of positioning a plurality of independently movable crimping dies against the surface of said ferrule and sequentially forcing each of said dies into said ferrule through a minor portion of its total travel while maintaining the inactive ones of said dies against the surface of said ferrule.

9. A method of securing a ferrule to a wire extending within said ferrule comprising the steps of: forcing a first crimping die against the external surface of said ferrule and into indenting relationship therewith to partially form a first indentation therein, maintaining said first crimping die against said ferrule without further indentation while forcing a second crimping die against the external surface of said ferrule and into indenting relationship therewith to partially form a second indentation therein, and repetitively forcing said first crimping die and said second crimping die in alternating order into said ferrule while maintaining the inactive one of said dies against said ferrule thereby incrementally to form a pair of indentations in said ferrule and crimp said ferrule onto said wire.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Jan. 19, 1955 

